What Happens If... You Don't Sleep?

We've all had nights where we fear we'll never doze off again.
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Sleep can be exceptionally elusive sometimes, for a whole host of reasons.

Too stressed, too ill or (this one really takes the biscuit) too exhausted. Occasionally, your body seems to refuse any attempts to nod off.

We all know by now how important sleep is to our general wellbeing, along with maintaining a healthy diet and fitness, with most adults needing between seven and nine hours of shut-eye every night.

But what happens if you just don’t sleep?

24 hours without sleep

At 24 hours without sleep, your body’s stress hormones will kick in – cortisol and adrenaline will try to compensate for your fatigue, according to US health company, Everyday Health.

Studies have compared this level of sleep deprivation to the cognitive impairment of someone with a blood alcohol content of 0.1%, meaning you have reduced reaction time, slurred speech and slowed thinking.

Your emotional reactions are increased, your ability to pay attention decreased, while your hearing is impaired – and you’re more likely to get into a fatal accident.

A study published in the Journal of Sleep Research back in 2016 also suggested that no sleep means you’re more likely to recall false memories.

36 hours without sleep

At 36 hours, things obviously get worse. Your risk of cardiovascular disease goes up, as your blood pressure remains at such a high level. That’s because it normally decreases in your sleep.

Your emotions will also be chaotic at best, with anxiety and mood swings becoming increasingly likely, while slow cognitive function will reduce your ability to concentrate and process information.

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48 hours without sleep

By the time you get to this benchmark, your body tries to go into “microsleep” mode. That’s a three to 15 second burst of rest where your brain just powers down, because it’s struggling to keep you awake.

You don’t even need to close your eyes for this to happen, according to Dr Michelle Drerup, psychologist and director of the Behavioural Sleep Medicine Programme at the Cleveland Clinic.

You might not even be aware that you’ve had a microsleep. The Sleep Foundation explains: “Regardless of how someone appears during a microsleep episode, their brain is not processing external information like usual.”

Of course, you’ll also be anxious, irritated, with brain fog and impaired cognitive function – and a few people might even experience hallucinations.

72 hours without sleep

As you can imagine, this is pretty horrendous and you’re likely to feel exceptionally on edge.

Expect an increased heart rate, negative mood, and a generally more fragile state, with more frequent microsleeps which have also increased in length.

This is when you’re most likely to experience more complex hallucinations, delusions and paranoia, according to Everyday Health. US-based health website Healthline suggests you might even experience depersonalisation – where you have the feeling of being outside yourself and observing your actions, feelings or thoughts from a distance.

96+ hours without sleep

Healthline explained that at this point (four days) your “perception of reality will be severely distorted” – a term also known as sleep deprivation psychosis.

Your body will also be almost forcing you to sleep.

Luckily, if you do start sleeping again at this point, you should be able to reverse the sleep deprivation psychosis.

According to The Guinness World Records, the longest known time a human was ever awake was 18 days, 21 hours and 40 minutes back in 1986.

But since 1997, the organisation has stopped recording efforts to stay awake because of the dangerous side-effects.

Chronic sleep deprivation

The Cleveland Clinic points out that, even if you sleep every night but just don’t get enough each time, you’re still at higher risk of:

  • High blood pressure
  • Diabetes
  • Heart attack
  • Heart failure
  • Stroke
  • Obesity
  • Depression
  • Reduced immune system function
  • Lower sex drive

You could also experience premature wrinkling and dark eye circles, along with a spike in the primary stress hormone cortisol.

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